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Staying cool without refrigerants: Next-generation Peltier cooling

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Re: Staying cool without refrigerants: Next-generation Peltier cooling

#101

Post by [deleted] »

madaxe_again wrote: post #60
fghorow wrote: post #27

For those worried about tiny COPs from these gizmos, trawling through the actual paper -- as well as the PR from JHU APL -- in this HN post [1] shows claims of COPs of ~15 for Delta Ts of 1.3°C. A compressor based cooler gets a COP of about 4 in the real world. I'm pretty sure this is an apples to oranges comparison to an expert (I am not one of those) but a factor of 3+ increase in COP is fairly noteworthy -- if it…

The delta of 1.3C is critical there - peltier cooling drops precipitously in efficiency as the delta increases, and struggles to hit a COP of even 1 in real world scenarios. Their figure works out at about 6.5% Carnot efficiency, whereas a normal heat pump is usually nearer 45% over a much broader range of temperatures, as you can separate the hot and cold sides completely. Not so with a peltier wafer. What they’ve d…

[deleted]

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#103

Post by esseph »

frosted-flakes wrote: post #99
esseph wrote: post #46

Earlier quoted context omitted.

You can hear your refrigerator???

You can't? Refrigerators have always made a noticeable background noise as they cycle on and off. The advantage of the newer variable speed scroll compressors in some high end fridges is that they can run continuously at a slower speed.

In an "open home" concept I guess it might make sense, but I've never lived in a place like that.

I guess all of the places I've lived the kitchen was always its own room, maybe adjacent to the dining room if anything.

No new appliances (>10y now I think about it, they came with the house.)

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#104

Post by theluketaylor »

tasty_freeze wrote: post #81
theluketaylor wrote: post #59

Earlier quoted context omitted.

With home HVAC, fridges, water heaters, and dryers all using now able to use of dependent on heat pumps I wonder how long it be before we see modular appliances that connect to coolant lines where the temperature differential is supplied by a central high efficiency heat pump. Cars already have heat scavenging that can move heat from where it's being created through losses to places where it's valuable, like the cabi…

That is an interesting thought, but I assume that the working ranges of the different appliances are different so there would be some complexities and inefficiencies getting them all connected to a common circulation loop. If there was a thermal equivalent of a transformer used for alternating current, that would be amazing.

As far as I know all the common commercially available heat pump appliances all use the same refrigerants, so it doesn't seem like it would be that challenging.

In cars that have unified heat management the refrigerant cycle is handled as a separate element, with a manifold controlling individual coolant loops to each component. I'm picturing something similar for the home, with a coolant moving heat to and from each appliance using standardized communication to the manifold. There would probably need to be heat buffer tanks, but air to water heat pump systems for radiant heat already need this anyway.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#105

Post by esseph »

userbinator wrote: post #64
bob1029 wrote: post #55

Earlier quoted context omitted.

The latest wave of appliances is really fucking loud for some reason. I think they're using different kinds of motor windings, bearings, insulation, etc. it's not related to the refrigerant or other system parameters. I've had older r600a fridges that were dead silent compared to anything sitting in a Best Buy showroom right now.

Likely high speed compressors --- the oldest hermetic systems used an induction motor running at 1800 RPM, then later they went to 3600 RPM, and now they're running on a VFD that possibly goes much faster. By making it pump faster, they can use a smaller compressor and reduce costs, at the expense of longevity and noise.

Ew.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#106

Post by JoshTriplett »

esseph wrote: post #46
Tistron wrote: post #16

What I want is a silent refrigerator, will this bring that? pray

You can hear your refrigerator???

Yes, absolutely. In particular, I find this obnoxious when staying in hotel rooms that have a minifridge.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#107

Post by [deleted] »

theluketaylor wrote: post #59
bob1029 wrote: post #29

Earlier quoted context omitted.

I've been thinking about what it would look like to convert my GE fridge into a minisplit (i.e., move the compressor, condensing coil & fan outside). You can buy R600a on Amazon right now. One $60 can will charge the system ~5 times.

With home HVAC, fridges, water heaters, and dryers all using now able to use of dependent on heat pumps I wonder how long it be before we see modular appliances that connect to coolant lines where the temperature differential is supplied by a central high efficiency heat pump. Cars already have heat scavenging that can move heat from where it's being created through losses to places where it's valuable, like the cabi…

[deleted]

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#108

Post by hypercube33 »

Aurornis wrote: post #25
WarOnPrivacy wrote: post #2

I used peltier coolers on K6 processors 1M computer years ago. They worked great and lasted about as long as the PCs did. Not long after I bought mine, they disappeared from cooler offerings. I've wondered what became of the tech.

Your K6 processor has a TDP somewhere around 20-30W depending on the model. Modern performance CPUs have TDPs in the 100-200W range. Peltier cooling generates a lot of additional heat. It doesn’t scale well to the higher loads. That’s why you don’t see them any more.

I'd consider performance processors something like a threadripper - 300W unlockable to 1000W. I haven't kept up with intel but I think they were indeed riding 200 to 300w.

Re: Staying cool without refrigerants: Next-generation Peltier cooling

#110

Post by throwawayoldie »

rcxdude wrote: post #73
BearOso wrote: post #8

AI has literally nothing to do with this. Why do they feel the need to sprinkle the phrase everywhere? AI inverter/compressor? Come on, have some sense of shame, please.

It's the name of the game, alas. In the area I work in, I've seen many companies get many multiples of the investment we've gotten because it's "quantum", even though they're trying to do the same thing we're doing and doing less well at it.

I assume that if you have "quantum AI", VCs break into your house and force bags of money on you.
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